Vacouver Street Trees

Data Visualization Analysis | Pankti Shah | December 2021

Introduction

Motivation:

City trees are important: they purify the air, reduce heat islands, help regulate the water cycle and provide immense health benefits.Trees play an important role in increasing urban biodiversity, providing plants and animals with a favourable habitat, food and protection. A mature tree absorbs greater CO2 per year. As a result, trees play an important role in climate change mitigation. Especially in cities with high levels of pollution, trees can improve air quality, making cities healthier places to live in.

Large trees are excellent filters for urban pollutants and fine particulates. They absorb pollutant gases (such as carbon monoxide, nitrogen oxides, ozone and sulfer oxides) and filter dust, dirt or smoke out of the air by trapping them on leaves and bark. Living in close proximity of urban green spaces and having access to them can improve physical and mental health. This, in turn, contributes to the well-being of urban communities.

Trees also help to reduce carbon emissions by helping to conserve energy. For example, the correct placement of trees around buildings can reduce the need for air conditioning, and reduce winter heating bills. Not to mention planning urban landscapes with trees can increase property value, and attract tourism and businesses.

Given these motivations, questions I will be exploring are:

  1. Evalute relationship between height and diameter of the tree with its age (planted date). This is to help understand does the age of a tree mean larger diamter or height. By understanding consistency of plating trees, distribution of age, height, and diameter of trees in Vancouver, we can understand if certain neighbourhood are more preferred for living, and improve tree planting strategy in the city.
  2. Evaluate species distribution across Vancouver neighbourhood (ie., popular species across Vancouver neighbourhood). This is to help understand biodiversity of trees across the city.

Analysis

Importing data, dropping columns that will not be helpful to answer questions stated in the introduction. Converting date_plated column into year, month, and day. Dropping all rows that have a missing value.

We are using about ~2300 datapoints in this analysis. Dataset contains 109 unique species and 22 unique neighbourhoods in Vancouver. Dataset also contains information about when a tree was planted, and its associated diameter, height, genus name, which side of the street it is planted along with various other miscellaneous information. Latitude and longitude of the tree are also provided. All the null values in the dataset have been removed to enable conducting adequate data analysis. Additional columns were added to the original dataset. New columns are height to diameter ratio of a tree and date_planted column being split into year, month, and day.

To explore answer to the first question, I will be using the columns year, height_range_id, diameter and height_diameter_ratio, latitude and longitude. Information from these columns will help evalute relationship between height and diameter of the tree with its age (planted date).

To explore answer to the second question, I will be using the columns species_name, neighbourhood_name, latitude and longitude. Information from these columns will help evaluate species distribution across the city of Vancouver.

Figure 1 above shows that generally 80+ trees were planted from the year 1995 to 2013. Outside these dates, there has been significant cut in number of trees planted. In most recent years, the city has planted less than 25 trees each year.

Figure 2 shows us that older the tree, greater its height on average. This makes sense considering plants tend to grow taller over a longer duration of time. Considering that an unequal number of trees were planted each year, we do have some discrepancies. However, overall we can say with age, trees tend to be taller.

Figure 3 shows us that older the tree, greater its diameter on average. This makes sense considering plants tend to grow wider over a longer duration of time. Considering that an unequal number of trees were planted each year, we do have some discrepancies. However, overall we can say with age, trees tend to be wider.

Figure 4 shows us that generally height to diameter ratio is more or less consistent across the years. We can therefore assume most tree species grow taller and wider at a similar rate. Average range of height to diameter ratio is between 0.3 - 0.35.

Figures 5 and 6 shows diameter and height of trees planted from 1989 to 2019, respectively. They allow us to understand the data more effectively, in case averages used in the previous figures were not adequate. From the data, we can clearly see outliers and this helps us justify why averages from some years did not follow the trend. For example, data points from 1998 are more sparsed and have clear outliers which led to have averages that are slightly higher than anticipated. However, for the purpose of this analysis we will not be removing any outliers from the dataset.

Next, we will explore distribution of height and diameter of the trees across various Vancouver neighbourhoods.

Previously, we found higher diameter and heights are associated with older trees. Hasting-Sunrise neighbourhood has the greatest number of older trees. Distribution of age of the tree is quite uneven across the city. However, generally the northern side of the city has bigger or more older trees than southern.

Figure 7 shows following as the most popular tree species being planted across Vancouver: Platanoides, Rubrum, Slyvatica, Cerasifera, Campsestre, Betulus, Freemani X, Americana, Serrulata, Euchlora X. From the total of 107 unique species, above top 10 make up most of the species.

Dashboard

Description of the dashboard panel below.

In total we have 2 interactive maps, 4 interactive bar plots, 2 scatter plots interacted by slider widget, and heat map and bar plot that interact with each other through dropdown widget.

Discussion

Summary

Trees now have a fundamental place in many big cities around the world. Large trees are excellent filters for urban pollutants and fine particulates. They absorb pollutant gases and filter dust, dirt or smoke out of the air by trapping them on leaves and bark. Living in close proximity of urban green spaces and having access to them can improve physical and mental health. This, in turn, contributes to the well-being of urban communities. Trees also help to reduce carbon emissions by helping to conserve energy, can increase property value, and attract tourism and business.

Given these motivation, I was using 'Vancouver trees' dataset to evaluate relationship between height, diameter of the tree with its age. Also, I was looking to understand distribution of the tree species, age, height, and diameter across Vancouver.

I was using about ~2300 datapoints; dataset contained 109 unique species and 22 unique neighbourhood in Vancouver. All the null values in the dataset were removed to conduct adequate data analysis.

From various visualizations, following was determined:

Conclusion

Trees are important part of urbanization. Given that there are numerous benefits of having trees in a neighbourhood, it is important for cities to keep evaluating tree biodiversity and keep up with new plantations as required. Benefits of having older trees are especially important. Typically, older trees have greater height and diameter measures. However, we can look into investing in a unique tree species that will grow quicker than others. The most popular tree species in Vancouver is Platanoides; they are most popular in Hasting-Sunrise neighbourhood.

In future, it would be interesting to evaluate the data to answer following additional questions:

References

Not all the work in this notebook is original. Parts that were borrowed from other resources are as follows: